Answer: use a wallpaper stripper or a damp sponge with a suitable product
Hello Anne-Coralie, to remove the last layer of wallpaper on your Placo® wall, you need a wallpaper stripper (steam) or possibly a wet sponge with a specific product to peel off the paper. If you are directly on the Placo® cardboard, do not soak the sponge much to remove only a thin layer of cardboard. If the Placo® is old, pieces of plaster may come with the rest of the wallpaper. In this case, you will need to reseal with Placo® glue and then sand. Then you can apply a primer and finally a new wallpaper.